Butternut (Juglans cinerea L.) Identification
Butternut (Juglans cinerea L.) Identification*
The butternut is a member of the walnut family and is widespread and native to southern Ontario, Quebec, as well as, New Brunswick. It is a small to medium size tree which rarely lives more than 75-100 years. Butternuts are shade intolerant and thus are generaly found in younger forests or in areas with open canopies. Individuals can be found individually or in small groups within mixed deciduous forests, along fence lines and drains, or in open fields.
Butternuts growing in open conditions have short trunks with a broad, open, spreading crown. Conversely, trees growing in a forest have taller less branchy trunks with smaller, more compact crowns (see Figure 3).
Figure 3: Picture of butternut trees growing in the open and in forested conditions.
Buds are arranged alternately along a twig and there can be two buds above each leaf scar. There is also a large terminal bud at the end of each twig. The buds are blunt, tan-coloured and hairy (see Figure 4).
Figure 4: Butternut vs black walnut buds and pith.
The bark of immature or younger trees is grey and smooth. As the tree ages and grows the bark becomes separated by narrow, dark fissures into wide, irregular flat topped, intersecting ridges (see Figure 5).
Figure 5: Butternut (immature and mature) bark vs black walnut bark
The leaves are compound, 25-40 cm in length, and are composed of 11-17 leaflets arranged along a central stalk. The individual leaflets are stalkless unlike those of the black walnut which have stalks. The terminal leaflet on butternuts is present and is relatively the same size as its neighbours unlike the black walnut whose terminal leaflet is reduced in size or absent. The butternut produces its leaves late in the spring and drops them early in the fall when compared to other native species (see Figure 6).
Figure 6: Butternut leaf vs black walnut leaf
The male and female flowers of the butternut occur on the same tree but mature at different times. Male flowers open first before the leaves and female flowers open at the same time as the leaves. The female flowers are wind pollinated and the nuts mature over the summer. Generally the nuts drop after the leave upon the arrival of the first heavy frost (see Figure 7).
Figure 7: Butternut male and female flowers
The nuts of the butternut are edible and nutritious. They are consumed by a variety of wildlife species and humans. The nuts of the butternut are pointed (about twice as long, 5-7 cm, as wide). The nuts develop singly or in clusters of 2 to 5 and have husks yellow/green in colour with dense sticky hairs. With the husk removed the shell of the nut has jagged ridges (see Figure 8).
Figure 8: Butternut nut vs black walnut nut
*Forest Gene Conservation Association. n.d. Butternut Tree – A Landowner’s Resource Guide. Forest Gene Conservation Association. Peterborough, Ontario. Available online at < http://www.fgca.net/conservation/sar/pdf/Butternut_LO_Guide.pdf>.